| Summary: | 1 poster.-- 2018 Ocean Sciences Meeting, 11-16 February, Portland, Oregon, USA From 2002 to 2016, a biennial transoceanic section from Portugal to Greenland (Ovide section/GO-SHIP-A25 line, Fig. 1) was performed as part of the CLIVAR and GOSHIP programs. The marine CO2 system parameters were measured to study their temporal variability due to natural and anthropogenic drivers. The rather deep Aragonite Saturation Horizon (ASH) in the Irminger Sea has been experiencing a very rapid shoaling mainly due to the rapid penetration of the anthropogenic CO2. From 1991 to 2016, the ASH shoaled 12-14 m year-1 for the intermediate waters in the Irminger Sea. The deep-convection events occurred during severe winters (1991-1994 and 2015-2106) fostered the fast addition of more acidified water into the deep layers of the North Atlantic. We calculated the increase in anthropogenic CO2 during the last two decades (2002-2016) and its concomitant decrease in the excess of calcium carbonate over the aragonite saturation levels. We found a reduction of about 1/3 in the transport of ion carbonate excess over the saturation levels with respect to the natural CO2 cycle for the period 2002-2016. The projection of these results to a future scenario where the atmospheric CO2 is 500±20 ppm indicates that the export of the aragonite saturated waters to the deep Atlantic associated with the thermohaline circulation would be reduced in nearly 2/3, which will have a negative impact in the deep habitats based in carbonate structures Peer reviewed
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